In patients with locally advanced or metastatic tumors, first-line therapeutic management is based on the use of targeted therapies (EGFR, BRAF ALK and ROS1 inhibitors), immunotherapies (anti-PD1/ anti-PDL1-antibodies or chemotherapy.

Despite patient selection based on histo-pathological and molecular criteria, not all patients respond to treatment. There are currently no markers to definitively guarantee a patient's response.

An alternative is to identify early patient response to treatment. The investigator hypothesize that change in circulating tumor DNA concentration (ctDNA) allow to early identify patients' therapeutic response (and non-response) of patients, regardless of the type of treatment used in the first line setting.

The primary objective is to determine whether early evolution (between baseline and week 3) of circulating tumor DNA concentration predicts the radiological response to first-line treatment of advanced or metastatic NSCLC patients, regardless of treatment

Inclusion Criteria:

• Metastatic or locally advanced non-small cell lung cancer (stage III or IV)
• At least one measurable target according to RECIST criteria
• Identification of at least one molecular alteration in the tissue sample analyzed in the framework of patient management
• Performance Status 0 to 2
• Affiliated to a social security system
• Patient who can be followed under the protocol
• Patient agreed to participate in the study and gave his/her express consent

Exclusion Criteria:

• Minor
• Small cell or mixed bronchial cancer
• Radiotherapy (except radiotherapy for antalgic purposes) during the last 7 days
• Patient who has already started a first line of treatment
• Patient already included in an interventional research protocol that may have an impact on the results of the ELUCID study
• History of cancer (with the exception of non-melanoma skin, cervical cancer in situ, adequately treated) with sign of illness during the last 5 years
• Patient which, does present a substantial risk of recurrence.
• Major under guardianship, curators or deprived of liberty
• Pregnant or lactating woman, or of childbearing age without effective contraception
• Not affiliated to a social security system
• Inability to understand the protocol and / or to give express consent